TABLE 7-5 Estimates of Folacin Requirement

Species

Age

Body Weight

Daily AirDry Diet Consumption

Type of Diet

Folacin Concentrations Studied

Criteria

Estimated Requirement

Reference

Macaca mulatta

Young, immature

2-3 kg

About 88 g for 2.0 to 2.5 kg monkeys

Casein, rice, wheat, mineral mix, vitamin mix

30-150 µg·d-1

Prevent anemia and leukopenia

60-100 µg·d-1

Day and Totter, 1947

Macaca mulatta

Young, immature

2.1-2.9 kg

About 88 g

Casein, rice, wheat, mineral mix, vitamin mix

N/A

Additional unpublished data indicated 100 µg daily dose required. Basal diet furnished 19 µg·d-1 (Day and Totter, 1947).

119 µg·d-1

Day and Totter, 1948

Saimiri sciureus

12-38 months

440-710 g

Not specified

Purified

0-0.84 mg·kg-1 air-dry diet.

Growth and normal hematologic status

75 µg·BWkg-1·d-1 furnished by 0.84 mg·kg-1 of air-dry diet. Liver folic acid concentrations low compared with other colony animals.

Rasmussen et al., 1979

Saimiri sciureus

Breeding adults

665 g

Not specified

Natural ingredients

1.43 mg·kg-1 air-dry diet compared with supplementation with 80 µg·d-1 5 days·week-1

Hematologic status, folate status, maternal weight gain during pregnancy, infant birth weight

3.0 mg·kg-1 of air dry matter

Rasmussen et al., 1980, Rasmusen, 1979

Cebus albifrons

3 years

1,570-2,170 g

 

Purified

0-1.05 mg·kg-1 of air-dry diet

Growth and normal hematologic status

45-75 µg·kg-1

Rasmussen et al., 1992

not known how nonhuman primates, consuming only plant material, obtain this vitamin, but it is possible that vitamin B12 is synthesized by microorganisms in the gastrointestinal tract (Uphill et al., 1977). Primates that practice coprophagy may obtain vitamin B12 from ingested feces (Oxnard, 1989). Little is known about the biologic availability of vitamin B12 in natural food ingredients (Baker, 1995). Supplemental vitamin B12 is usually added to animal feeds as cyanocobalamin.

The signs of vitamin B12 deficiency in humans are megaloblastic anemia and progressive demyelination and neuropathy (Herbert, 1996). A frank deficiency of vitamin B12 was produced under controlled conditions in rhesus monkeys (Macaca mulatta) by feeding a purified diet containing soy protein rather than casein to avoid potential contamination by vitamin B12 in the latter. During the first 12-18 months, serum concentrations of B12 dropped to 5-10% of initial values. Liver vitamin B12 concentrations were less than 5% of those in supplemented animals. Methlymalonic acid concentrations in the urine, a biochemical indicator of deficiency, increased in deficient animals but not in supplemented controls. In spite of the apparent depletion of vitamin B12 stores, no other manifestations of deficiency were seen (Kark et al., 1974). The studies were then extended. Monkeys fed the deficient diet for a total of 33-45 months exhibited additional deficiency signs, including visual impairment that gradually progressed to blindness, spastic paralysis of the hind limbs and tail, general weakness, apathy, and death. At necropsy, degeneration of nervous tissue was evident, with eventual destruction of the myelin sheath and loss of axons (Agamanolis et al., 1976, 1978; Chester et al., 1980). The degeneration of central nervous tissue was similar to “subacute combined degeneration,” one of the clinical diseases seen in human vitamin B12 deficiency. Even in the most severe cases of vitamin B12 deficiency, no signs of anemia or any other blood disorders were observed.

Chronic deficiency of vitamin B12 in nonhuman primates under somewhat less controlled conditions has also been described. Blood concentrations of vitamin B12 in newly



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement